Popular Science Monthly/Volume 13/August 1878/Man and his Structural Affinities
|MAN AND HIS STRUCTURAL AFFINITIES.|
AN average coroner's jury might sit on the skeleton of an anthropoid ape and return a verdict that the deceased came to his death at the hands of parties unknown, with the sublime consciousness of having performed their duty and earned their fees. The suspicions of the more intelligent jurymen might easily be allayed by the common conception of what the word "monstrosity" will cover, and the similarity is indeed so great that I see no reason why the verdict should not be unanimous.
The gorilla has no more tail than a professor, while the knowledge that monkeys have tails, and the idea that these external appendages are a badge of general monkeyhood, are deeply rooted in the popular mind. But the apes are as tailless as man is, and no more so. I might say even less so, for the gorilla seems to have one caudal vertebra less than man; but we must give more weight to the head than the tail in matters of classification. In this world heads win throughout the game of life. Certainly, the bones of a gorilla, for instance, may be readily distinguished from those of a man, but certain bones in woman differ also slightly from the corresponding ones in man, and it is a recorded fact that juries have in this way mistaken the sex of the human subject of their deliberations. In England, in 1839, a double jury sat on the skeleton of a woman accidentally found, and upon which a man had been arrested for the supposed murder of his brother, for whose remains the bones had been mistaken. Their real nature fortunately transpired before a verdict was rendered. It is evident, however, that the bones of extinct animals have been mistaken for human remains, and so have inspired accounts of prehistoric giants; while it is certain that the bones of fossil mammalia have been revered as relics in Europe during the middle ages, and even up to the time of Cuvier. The correct determination of bones is, indeed, a more difficult matter than may be supposed from the readiness with which naturalists sometimes deal with the subject. A great deal depends on the state of preservation of the bone; and, again, what particular bone it is. Certain single bones, as the tooth, or one of the bones of the feet or hands, are much more decisive in their character than the ribs or vertebræ. The structure of the teeth shows a relation to the character and consistency of the food, and there is no doubt that, so long as the lion has his present dentition, and while his appetite remains, he will always lie down with the lamb—inside of him. In land-animals the bones of the limbs have more play in their sockets than in air or water animals, because flexibility is necessary to speed over the ground or trees, but it is an objection where the limbs are to be used as paddles against the air or water. In fact, the more we know of the skeleton and the environment of the animal, the more we see that its variations throughout the animal kingdom are the combined results of the movements of the organism itself and the opposition of the medium in which it moves. Where the actions of the animal are slow, it is found that the bones of the limbs are more rigid and often joined, as shown in the case of the sloth by Prof. Cope. The head and the ends of the limbs, being in constant use against the vital conditions of the environment, are the soonest modified. The bones are formed by the muscles, and the muscles are developed through the movement of the animal. We may all have noticed that, when the skin is stripped off, and the extremities of the backbone, the head and tail, are cut off, together with the feet, the carcass of a cat looks much like that of a rabbit in the same condition.
Those who have not investigated such an instance of similarity, yet know that in a butcher's shop there is a superficial sameness in the appearance of meat which it is the business of a good marketer to see through; while a good many of us, who are unaccustomed to provide, would no doubt be not a little puzzled to distinguish the body of a calf from that of a sheep as it hangs in the stalls. The same thing holds good with the bodies of birds and other animals: a duck is identified most quickly by the webbed feet and flattened bill. Thus it is a matter, perhaps, of general knowledge that an animal is difficult to recognize when the head and extremities of the limbs are missing, and we see now the reason that it is so. We may go even further than this and account for the mistakes of antiquity on the same principle. It is not credible that the head or feet of a mammoth could have been mistaken for those of a man, nor were they as a fact; but a thigh-bone, or rib, offered less difficulty by reason of the greater resemblance. Hence we find that these mistakes have been made with some excuse for their commission. The difference existing between these fossils and the corresponding bone in man was so small as to escape the notice of the anatomists of antiquity. The general resemblance between the skeletons of all vertebrate animals was not then fully appreciated. People distinguished the animals in old times from man by their heads, feet, and fur, to say nothing of their tails; and, when they found an isolated internal bone, they may readily be forgiven for having wrongly referred it.
Again, the bones being produced through the muscles, and these through the nutrition of the animal, there is always a proportion between the skeleton and the stomach and soft parts of the body. The skeleton is a very good index of the comparative bulk of the animal, and this fact assists us when we attempt restorations of extinct species.
From the herd of monkeys found in the Oriental and Ethiopian regions of the Old World, the apes are readily distinguished by certain structural characters. The body is that of a human being, except that the arms are proportionally longer, and the legs shorter, than in the average man. The face is very human from the structure and position of the eyes and ears. A tail, external to the rump, is entirely wanting. The body is covered with sparse and soft hair, except the face, toes, palms, and soles, which are bare. The species which has been written about the most, and about which, strange to say, we know the least, is the gorilla (Gorilla Savagei). Whether this ape was the species called by this name two thousand years ago by Hanno is doubtful and of no importance.
Wilson and Savage, two American missionaries, seem to have been the first, in 1846 and 1847, to bring us certain information of this comparatively near relative of ours. I do not think that we are grateful for the discovery. Generally speaking, we could have dispensed with this satire upon ourselves, although we have no responsibility in the case. At any rate, we can appreciate one value of missionary labor. American missionaries, by their intelligence and perseverance, have given us invaluable information from time to time concerning countries difficult of access, and their strange inhabitants.
Since this discovery of the gorilla, the animal has been written about by several travelers. The accounts of personal encounter furnished by Du Chaillu are now known to be largely fanciful; and Winwood Reade, a most reliable traveler, doubts if an adult has ever jet been seen alive in its native haunts by a white man. The specimens sent alive to Europe, and which have been claimed to be gorillas, have almost always turned out to be chimpanzees in various stages of growth. But the skulls and skins sent by Dr. Savage have been followed up by complete skeletons and preparations sent by other travelers, and naturalists have been able thus to study the appearance and structure of the most formidable of the man-apes, which is credibly stated to inhabit Central Africa from Sierra Leone in the north to Loango in the south. Living in the dense forests of that region and avoiding the presence of, it is only with difficulty they are to be met with, and, from the inefficiency of negro courage and weapons they are rarely killed. We have thus no authentic portrait of the live adult gorilla, but we give here (Fig. 1) a picture of the head of a young male gorilla preserved in spirits in the collection of the Society of Natural Sciences of Hamburg.
|Fig. 2.—Skeleton of Gorilla, and Male (a) and Female (b) Skulls.|
In comparing the skeleton of the adult gorilla with that of man, we find that the vertebral column offers slight and unimportant differences. The number of ribs is thirteen; while in man it is usually twelve, but occasionally also thirteen are found. The curve of the back is slightly different because the erect position is not always maintained, and to this circumstance I would also attribute the difference in the shape of the pelvis. In man the viscera have to be supported during his usually erect position, and the bones of the pelvic girdle are larger, giving space for the attachment of the larger muscles of the spine and thighs, which render the attitude possible without inconvenient fatigue. But it is a fact that in a child, before it learns to walk, the pelvis is as contracted as in the apes. In its efforts to walk the girdle is opened out, the sutures being flexible during childhood. When we come to the skull of the gorilla, we find a great difference in the relative proportion of the different parts. The bones of the face are large and the jaws project. There is a variation in the different races of man in this respect, as an examination of the skulls of different races shows. The relative large size of the jaws and lower parts of the face we see in the negro races especially, as compared with our own, and to this type we give the name prognathic.
The man-apes show an excessive development of this type. At first sight this large development of the lower face and jaws might distinguish the apes from man with great clearness, but its importance seems diminished when we compare the man-apes with the baboons and lower, tailed monkeys in this respect. The cranium of the gorilla is also very small in proportion to that of man. The contents of the smallest skull of man is given at sixty-two cubic inches; that of an adult gorilla is given at thirty-four cubic inches. But this difference loses much of its value when we see the amount of variation in men of the skull measurements. Thus the largest human skull shows a capacity of 114 cubic inches, being about twice the size of the smallest adult human skull.
Now, the difference thus shown in man of fifty-two cubic inches between the capacity of the largest and smallest skulls is greater than that between the smallest human skull and that of the gorilla, which is only twenty-seven inches. These figures will probably be still further modified so soon as we get accurate measurements of the skulls of certain African and Indian hill tribes more recently discovered. Indeed, it is already stated that twelve cubic inches of cranial capacity will cover the difference between the smallest human and the largest simian skull yet known. Again here, as with the prognathic characters, the importance of the difference in cranial size is diminished by the fact of its variation among the apes and monkeys, which latter are found to fall as much below the apes in cranial capacity as the apes do as compared with man. The skull of the gorilla exhibits considerable variation in the specimens which have been yet these fangs, we find, just as we did before, that there is a greater difference here between the man-apes and the lower monkeys than between the man-apes and man. The canines are either much more developed or there is a change in the total number of teeth indicative of a greater departure from the human type of dentition.. The males seem to have a prominent bony ridge on the crown of the skull, but this development of the bone stands in proportion to the muscles of the jaws which reach on each side up to the crest which they deposit. Where the jaws are weaker, as in the female, the crest is undeveloped, the muscles do not reach up so far and they deposit smaller ridges on the side of the skull. These crests are, however, wanting in the orang-outang, a lower kind of man-ape than the gorilla, where they are replaced by two bony ridges, a couple of inches apart, as we learn from Mr. Wallace's interesting writings. But the variation among the skulls of the gorilla yet examined is so great in the proportion of the different parts of the face, that it is evident there is a greater amount of individual peculiarity in this than in any other animal except man. This point is worthy of a much more extended examination than it is now possible to give to it. It is sufficient to state that these differences seem to have prompted Dr. Wyman and Du Chaillu to suspect species where in fact we find only one kind of gorilla as more specimens come to hand and supply the intermediary links. With regard to the permanent teeth of the gorilla they are thirty-two in number, just as in man. The principal difference is that the canine teeth, at least in the adult males, are longer than in man, and project. The jaws being more powerful and more constantly in use, the teeth are stronger and proportionally stouter than in man. And where we find any difference, such as is offered by the large canines, and the break in the lower series to admit of the play of
You will remember that I called attention to the fact that throughout the animal kingdom we were to find the greatest changes in the structure of the extremities of the limbs, because these were brought
into constant use against the immediate surroundings of the animal. In truth, the greatest differences between the gorilla and man are found in the feet. The hands are not very unlike a man's; every bone and muscle is here again in its place; the thumb is a little shorter and the whole hand heavier. The muscles of the arm are more powerful and the hand is used for coarser work than man's, but after all not for work very different in kind. With them the gorilla builds a nest to sleep in, breaks off boughs, handles its food, and also attacks its enemy, holding him fast so that it can bite him. We do all these things with our hands; and there is a legal term, mayhem, to denote the crime of mutilation with the teeth, which is not uncommon among brutal men of some countries considered civilized. But the foot seems at first very different from a man's, although here again every bone and the determining muscle (peroneus longus) of the foot of man are present. The foot is set more obliquely on the leg and the big-toe is farther from the rest, proportionally shorter and weaker, and, above all, more flexible. Certainly these important differences are connected with its mode of life, which is more arboreal than that of man.
With its foot the gorilla can steady itself in climbing and hold fast to objects from which the rigid foot of man would slide away. Still our feet are not wholly unfit for grasping, and you may have noticed barefooted boys cutting up "monkey-shines" on trees with entire safety to themselves, though not to the complete satisfaction of their parents. The female gorilla seems to consider her young one safe when he is up the tree; but the anxious human mother does not feel easy until the child is on the ground again. Circumstances thus alter cases throughout the range of experience. Again, we are familiar with the fact that men who have lost their arms often learn to write and perform other actions with their feet. But, notwithstanding these important differences between the feet of the gorilla and our own, there is again the greater difference to be considered between the hands and feet of the lower monkeys and those of the gorilla. The thumb ceases to be opposable in the American monkeys, and is again reduced to a mere rudiment covered by the skin in the spider-monkey. Indeed, we may say that, looking through the succession of simian forms, from below up, there is a constant increase of the characters which prepare us for man. And the gorilla exhibits these in their fullest development. From the gorilla it is indeed easy to predicate man—much easier than to suppose the gorilla from the lowest monkeys.
Another interesting man-ape is the chimpanzee (Chimpanza niger). Many living specimens have been brought to Europe and lately to New York from Africa, where it inhabits the same territory as the gorilla. It is a smaller species than the gorilla, the head proportionately larger and less prognathic, the arm shorter. The foot is more hand-like, and there is a slight difference in the dentition. In running, the chimpanzee goes on all-fours, but in walking or carrying anything the position it assumes is nearly erect. In captivity the chimpanzee has developed most amiable qualities. It has been taught to sit at table, and even to conform to what we esteem good manners. It becomes passionately fond of its keeper, clinging to him, and refusing to be separated on any occasion. It is extremely kind to children, showing no trickish or malicious temper, even endeavoring to amuse them, and induce them to play. As long as there is light in the room the chimpanzee will sit up at night; as soon as the light is withdrawn it goes to sleep, lying stretched out with its hands under its head if the temperature is pleasant, but, if cold, cowering together like a human being under similar circumstances. It is evident that much might be done with the chimpanzee to make him an agreeable companion to man. Fortunately, this hard fate may be spared to the chimpanzee, because he cannot support existence in the colder regions to which our race has become acclimated.
The negroes do not seem to court his companionship. One notable feature in the chimpanzee remains to be stated, and that is his peculiar behavior to other animals. He is perfectly contemptuous in his treatment of our small, domestic animals, such as rabbits. He is frightened at large and fierce dogs, and exhibits an extreme terror at snakes and ugly reptiles. In this latter fact we recognize a mental state which is still shared by man, suggesting the probable origin of the serpent as an embodiment of the devil in the ideas of primitive man, and which still survives among us at the present day. Another species of man-ape is the tschego (Anthropopithicus tschego), which is only known from a single living female brought to Dresden from Loango. This species seems to be but little smaller than the gorilla, intermediate in size between this and the chimpanzee. In the proportion of its parts the most notable peculiarity seems to be that the legs are longer than in the other man-apes. The behavior of the specimen in confinement did not differ greatly from that already related of the chimpanzee.
The Asiatic man-apes differ from those of Africa by the proportionally longer arms, which reach down to the ankles. The orang-outang (Simia satyrus) inhabits most commonly the island of Borneo, and has recently been collected in considerable numbers by Mr. Alfred Wallace. It has only twelve pairs of ribs, as is usual with man. The body is broad at the hips, and joined to a pyramidal-shaped head by a short neck, which is still further concealed by heavy folds of the skin, which can be puffed out by the animal when angry. The eyes and ears are small, but not unlike those of man. The nose is quite flat, the mouth is large and ugly, from the thick lips. The jaws are extremely powerful, and the canine teeth prominent. The breast is thinly haired, and the face, the fingers, palms, and soles, are naked. The back and top of the head are thickly haired, and on the side of the jaws the hair descends
like a beard. In color the hair is a dark, rusty red, sometimes brownish on the back, the fringing hair of the face usually lighter than the rest. The color of the skin is bluish-gray. The old males may be distinguished by their longer beards, which are wanting in the young, and by a peculiar swelling of the cheek from the eyes to the ears, which makes their aspect more repulsive.
The orang-outang was certainly known to the ancients, and Pliny gives an account of this species which has been extensively copied. One peculiarity, only recently observed, is that the skull undergoes a greater change in shape than usual during growth. The heads of baby-orangs bear a close resemblance to those of infants; but afterward the lower portion of the face increases rapidly in size, and the aspect of the adult is more repulsive and animal-like than the chimpanzee. Wallace says they frequent swampy localities in Sumatra and Borneo, and visit the orchards of the Dyaks for the purpose of devouring the fruit. They build nests in the trees, of boughs, in which they sleep. They climb with great ease, and traverse the forest from tree to tree in a semi-erect position, assisted by their long arms, and are capable of progressing at the rate of eight or nine miles an hour without any appearance of hurry or fatigue, going as fast as a man on the ground beneath them can run. The food of the orang-outang is strictly a vegetable one. It has the habit of not rising very early in the morning, waiting until the sun has dried the dews, and Nature has dressed herself for its appearance. Although the orang does not court danger, it does not seem afraid to fight if necessity obliges. Wallace narrates the combat between a Dyak and an orang, in which the native was terribly bitten and might have been killed had not assistance arrived. The orang was then killed by numbers, and Wallace rescued the skin and head to be added to his large collections, and taken later to England. Mr. Wallace also succeeded in finding a baby orang-outang, and gives his experience with it as follows:
This account is interesting, because it shows that in its actions the young orang-outang recalls what we are familiar with in infants; and again it illustrates the activity of the limbs at an early age and before they can be used intelligently. There can be no doubt that in this way we come to use our limbs at first, by a sort of blind groping in the uncertain light of infancy. We feel a sympathy for Mr. Wallace that his baby orang-outang never would do anything to reflect credit on its bringing-up, and finally died in an obstinate and childish manner. It was thought that it never entirely got over its separation from its family, but this may have been a fancy.
Another long-armed ape is the gibbon (Hylobates far), which is smaller than the orang-outang and exceedingly intelligent. This species readily assumes the erect position when not executing its incomparable gymnastic feats, swinging with its arms and leaping from one rope to another in the rooms fitted up for its dwelling in confinement. It walks with the knees bent and the long arms stretched out with the hands hanging down, reminding one of the position of a rope-walker. The gibbon is extremely neat and cleanly with its person, and is not distinguished by any peculiar odor, as are some of the other species of
apes. As a prisoner the gibbon eats bread, milk, and fruit. Before drinking, it has been remarked that it tastes the fluid doubtfully with the tip of the tongue, which in the apes, as in man, is the most sensitive portion of that organ. Dr. Hermes says that the gibbon is an aristocrat among the man-apes and always on the best behavior.
I conclude this outline description of the man-apes with the statement that the duration of life among them is not accurately known, and probably varies with the different species. The gorilla and chimpanzee probably attain the average age of man.
The position of science with regard to man and the anthropoid apes is, that in no case can these latter be considered our progenitors or descendants. The physical and mental characteristics are too diverse to admit of such conclusions. The apes have evidently come down another line of descent, although the time when both the apes and man may have emerged from a common branch of the tree of animal life may not be so very long past. But, whenever the line of man and that of the anthropoid apes coincided, it is clear that now the tendency must be to diverge more and more. The resemblances between the apes and man, however, cannot be overlooked by the thinking mind. They are so great that if we assumed the theory of degeneracy to be true, and so were willing to throw the whole animal kingdom backward on its tail instead of forward on its feet, we might consider them to be degenerate and "wild" men. And it is interesting to find that this is what they were formerly held to be. The early pictures of the orang and chimpanzee exemplify this notion by giving them perfectly human features and erect position, brutalized only by their hairy body. They were, in fact, assumed to be a very abandoned kind of man, and not a very elevated kind of monkey. It is thought by some tribes of men to this day that the apes could talk if they would, but they are afraid that if they do they will be made slaves of and obliged to work. From the naked white skin, through the yellow and red to the black and then to the black with hair, does, indeed, seem a gradual transition; and, if we concede the erect posture, the admission of the ape into the human family carries with it no little show of justice. It is not so long ago that we denied human rights, and both openly and impliedly consanguinity, to the negro, as to make it impossible that we should not come to regard the gorilla in a more affectionate light than we do at present. But, in point of fact, the different races of mankind represent a kinship remote in proportion to their structural differences; and most of us, perhaps, would be willing to admit at once the truth of this proposition. Science insists that it is true throughout the animal world, and expects that the time will come when it will be acknowledged, and our behavior improved by an increasing kindness on our part to our inferior and weaker fellow-inhabitants of the earth. The proof of the evolution of man we find first in the fact that for every bone and muscle or organ in man there is a corresponding one in the anthropoid apes. Having shown in this way that man is not separable from his physical characteristics, science enters into a comparison with regard to the difference in brain-power. The mass of the brain, as judged by the cubical contents of the cranium, we have seen, can be no certain criterion for the intelligence, but only of comparative value, because it was so variable in the apes and man. It is, however, a guide from a physiological point of view by which we can estimate an advance in thinking powers throughout the animal kingdom. It has been amply shown by Prof. Marsh that, as a whole, the proportion of the brain-case has increased through the succession of fossil vertebrate life from the time when coal was formed up to the present. And it can be shown that this proportion is greater in man to-day as compared with existing mammals. When we come to the structure of the mass of the brain, that of man offers no perceivable difference of importance from that of certain apes. The discussion on this point has been fully entered into by distinguished anatomists, and need not be detailed in this place. Alone, the weight offers a difference. The heaviest human brain known is given at 1,872 grammes, the lightest brain of a sane person 907 grammes, both these extremes being furnished by women. The difference between the mass of the brain of man and that of the gorilla is proportionally, perhaps, the greatest that exists to separate the two. It has been considered by Huxley to approximate to twelve ounces. But the difference between the extremes of brain-weight in man, as exemplified in the figures here given, shows that we cannot consider intelligence to depend on the weight of the brain. All that we can say is, that a man with a large brain has capacity for the display of intelligence. It depends on his use of the senses, which are the feeders of the intellect, whether he displays high wisdom or not. It is quite possible that an ape may be more intelligent than a human being who has not properly supplied his brain with information. Human beings born dumb and blind are not born ipso facto intelligent, but are taught with great trouble and patience through the channels of the remaining senses. The facts known in regard to afflicted persons are amply sufficient to warrant the statement that the intelligence depends on the senses, and if these are interfered with, either in the structure of the organs, or by giving them a limited opportunity for activity, you have, as a result, less intelligence in the individual, be it man or ape, or other animal. We can show that the difference between man and apes is a quantitative and not a qualitative one.
- From a lecture delivered before the Buffalo Society of Natural Sciences, March 9, 1878.